ISPConfig 3 and creating db mysql from panel

Hi guys,
I have a problem that occurred yesterday and is as follows:
In panel ISPConfig 3, I created a new user, domain, database, and ... surprise, the database is not created!
I made other attempts, but the problem persists. ISPC does not seem to make the necessary operations to create user / database.
Through the tool mysql with the command show databases, the database engine does not actually exist;
the query select * from mysql.user I verified that the user is not created.
I do not know how to fix it.
Please help me. Thank you!